1. Chapter 11.5
Linkage and Gene Maps

2. Gene Linkage
Thomas Hunt Morgan found that some genes did NOT assort independently. He reasoned that there were linkage groups, where certain genes were always inherited together.
What he really found was that these linkage groups were really genes on the same chromosomes. So chromosomes assort independently, not individual genes.

3. Gene Maps
If 2 genes are found on the same chromosome are they linked forever?
Crossing over can sometimes separate by crossing over. Crossing over separates linked genes and produces a new combination of alleles.
Alfred Sturtevant wanted to know how the rate of crossing over occurred. He said that if 2 genes were farther apart they would more likely be separated by crossing over.
From crossing over rates he was able to make a gene map showing the location of each gene in a fruit fly.